1. Field of the Invention
The present invention relates to a text processing apparatus comprising an internal storage device and an external storage device, wherein text data stored in the internal storage device and text data stored in the external storage device can be compared on a text unit basis or on a page unit basis.
2. Related Background Art
In general, in a text processing apparatus having an internal storage device, an external storage medium such as a hard disk device or the like has a larger capacity than that of the internal storage medium, so that all of the data in the external storage medium cannot be developed or transferred to in the internal storage medium. Therefore, in such a text processing apparatus, a program and data are sequentially read out of the external storage medium and stored in the internal storage medium, then various kinds of processes are executed and text editing is performed. In the text processing apparatus of such a type that necessary data is sequentially read out of the external storage medium and developed in the internal storage medium as described above, the external storage medium needs to be accessed at random. For the management of tasks and files, complicated processes such as display and the like are also necessary. On the other hand, in a text processing apparatus such as a word processor, electronic typewriter, or the like having a single function, an external storage medium such as an IC card, a RAM, an FDD, a cassette, or the like is used and at the same time, a ROM is provided as an internal storage medium for the main system. Texts, extended dictionary, display fonts, and the like are stored as external data and released for the user. Even those apparatuses cannot develop all of the text in the external storage medium in the internal storage medium when the text is edited. It is necessary to again store the text in the external storage medium after editing. The document processing apparatus as mentioned above has several disadvantages; for example; change points between the edited text file and task and the file and task in the external storage device before editing cannot be sufficiently known. Further, the disk needs to be accessed many times. Thus, the working efficiency of the device is very low.